Conventionally, a reservoir tank that is used in a brake device for a vehicle, provided with a master cylinder device for the vehicle and with a fluid pressure control device for the vehicle, is widely known. One example is shown in Japanese Unexamined Patent Application Publication No. 2002-67923.
In the reservoir tank of Japanese Unexamined Patent Application Publication No. 2002-67923, a float guide that forms a float chamber in a reservoir body is formed higher than in conventional approaches. According to the reservoir tank of this reference, even when the reservoir tank is in a forward-inclined orientation during braking of the vehicle, the required amount of fluid in the float chamber is secured, and the fluid level height in the float chamber is maintained.
A slit is formed in the float guide to prevent malfunction of a fluid level detection device. The slit is in communication with the float chamber and a storage chamber on the outer side, and functions as a flow channel for an operating fluid between the float chamber and the storage chamber.